Michael, Exposed Copper is a major concern associated with OSP. Those who used it and love it have convinced them selves that the exposed copper is not a defect. They do have a point. Before OSP, all the metal was solder coated, or some other metalic coating (ni/au). Any exposed copper was the result of the copper surface rejecting the coating that was being applied to it. This is a bad situation. Since copper will always allow solder to wet it, exposed copper is evidence that there is contamination on the board. The boards are rejected for contamination, AS EVIDENCED BY exposed copper. They are not rejected for exposed copper, per se. Many have forgotten why we reject boards for exposed copper. "It's just the way we have always done it." Further evidence of this distinction is found in the old Mil-P-55110 which allowed the vertical edges to have exposed copper after tin-lead reflow. Why? Since they were never coated with solder, visible copper is not evidence of contamination. Now we have OSP. (I think you can see where this is going.) Boards are shipped without solder coatings. If the solder paste does not cover the entire pad, it is likely there will be exposed copper after fusing. Is this evidence of contamination? No. Therefore, the argument goes, no contamination means no defect. On the other side, One asks, If there were contamination on the board, how would I know? The exposed copper is evidence of one of two things: 1) the copper was never coated; or 2) the copper rejected the solder because of contamination. Since I can't tell the difference, I will assume the worse case, and reject the board. [This argument goes back and forth a few more times, ie there are ways to tell the difference] There has been evidence that CLEAN exposed copper is just as good as solder coated copper from a long term reliability point of view. Some indications are that exposed copper is better that solder. So the choice is yours, or your companys. How will you define "exposed copper", as an indicator of contamination, or a rejectable cosmetic defect. Keep in mind the impact this choice can have on your companies future competitiveness. Personally, I think it is unfair to apply the process indicators (exposed copper) of one process (solder coating) to a fundamentally different process (OSP). -- George Franck Principal Product Engineer Raytheon E-Systems Falls Church Va "These views are my own. They may or may not be shared by my company" *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************